Republicans, however, have seen their collective image tank even more dramatically: The GOP's favorability rating has dropped a net 20 percentage points. In February, Republicans were viewed unfavorably, but only slightly: 43 percent of Americans had a positive view of the GOP, while 48 viewed the party negatively.

Now, just a third — 34 percent — of respondents told Pew they have a favorable view of the Republican Party. Fifty-nine percent have a negative view.

Pew's numbers on the GOP presidential primary generally confirm the conventional wisdom about the race. Seventy-seven percent of Republicans and Republican-leaning voters say there's "some chance" or a "good chance" that they'll vote for Rick Perry, topping the field. For Mitt Romney, that number is 75 percent, and for Bachmann it's 65 percent.

The loser by that measure is Newt Gingrich, who has 50 percent of Republicans saying there's "some chance" or a "good chance" that they'd support him, but 48 percent who say there's "no chance."